New fish is discovered in Maryland Unnamed species of sculpin lives in Potomac feeders

While many species of plants and animals are vanishing, a new freshwater fish has been "discovered" in the cold, rushing waters of streams that feed the Potomac River in western Maryland.

Only a handful of new fish are found each year around the world, so spotting one in a densely populated state is remarkable.

Richard Raesly, a biologist at Frostburg State University, identified the bizarre-looking member of the sculpin family, a fish with a big, flat head and upward-gazing eyes.

Apparently the fish has been around for eons, but other biologists mistook it for the slimy sculpin, a distant relative.

Such confusion is easy to understand, because sculpins are among the toughest fresh-water fish in North America to identify, according to Peterson's Field Guide to Freshwater Fishes. You need a microscope to tell some apart.

Dr. Raesly had a hunch, however, that what others thought was a slimy sculpin was really a unique, hitherto unnamed species of the same family. Biologists who had slogged through creeks along the Potomac before him had left tantalizing clues. One researcher noted finding an "undescribed species."

So Dr. Raesly persuaded Maryland's Department of Natural Resources to pay him $3,000 to solve the mystery of the fish's identity.

After careful examination of the fish's anatomy and genetic structure, he and colleague Ronald Gregg found some telling deviations. This fish has a different array of teeth, for instance, and fewer pores on its chin than the slimy sculpin has.

Now it appears the slimy sculpin, which is found from Canada south to Pennsylvania, does not live in Maryland at all. Dr. Raesly said he believes that the few fish previously identified in this state as slimy sculpins belong to this new species.

Dr. Raesly won't divulge the name he has given the new fish. In order for it to be officially accepted, his findings first must be published in Copeia, the journal of ichthyology and herpetology (translation: fishes and reptiles).

Although too small to interest anglers, the new fish could give scientists fresh insights into the murky process of evolution, Dr. Raesly says.

The fish probably appeared throughout the Potomac at one time. But as the region's waters warmed at the end of the Ice Age, its range shrank to streams with the coldest waters, usually fed by springs. The sculpin lurks at the bottom of riffles in the same type of pristine waters favored by trout.

"They'd be kind of fun to have in an aquarium at home, but in general they require a lot of oxygen and colder water than you'd have in your normal aquarium setup," he said.

It is too early to say whether the new species is rare enough to warrant government protection as threatened or endangered, said Janet McKegg, director of Maryland's Natural Heritage program. The slimy sculpin, now listed as endangered in this state, will be dropped from the list.

While the new sculpin seems abundant in those spots where it has been found, it is vulnerable because its populations are widely scattered,Dr. Raesly said. A sewage or farm manure spill could wipe out a whole group, or development could make the streams uninhabitable.

Dr. Raesly knows how vulnerable fish can be that are found only in a few isolated spots. Five years ago, he was the last person to see the Maryland Darter, a member of the perch family. Found in just one spot in Deer Creek in Harford County, it is now believed to be extinct.

"It's not like we're being God and replacing one species with another," said Rodney Bartgis, a state ecologist. "But it's kind of cool to discover something new."